Infrared Detector

ABSTRACT

Methods, systems, and apparatus, for an infrared detector are provided. In one aspect, an infrared detector is provided that includes a pyroelectric sensor; a controller for receiving a trigger signal outputted by the pyroelectric sensor; a thermopile sensor, wherein the controller starts the thermopile sensor after receiving the trigger signal output by the pyroelectric sensor; and an alarm, wherein when the thermopile sensor determines that a difference between a current temperature and a background temperature is larger than a threshold value, the controller controls the alarm to generate an alarm signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 of the filingdate of Chinese Patent Application No. 201410116794.8, for SmartInfrared Detector and Working Method Thereof, which was filed on Mar.26, 2014, and which is incorporated here by reference.

BACKGROUND

The present specification relates to infrared detectors.

Infrared detectors are often used to measure temperature changes withinan area such as a room being monitored. One typical type of infrareddetector includes a pyroelectric sensor. When a surface temperature ofthe pyroelectric sensor's dielectric changes, the dielectric generatesan electric charge. In particular, polarization of the material formingthe dielectric surface changes in response to a change in temperature,which generates a voltage across the dielectric. When the surfacetemperature rises, the polarization strength in the dielectric reduces,which results in a release of charge by the dielectric. The generatedcharge gradually drifts away from the dielectric surface. Infraredradiation incident upon the dielectric of the pyroelectric sensorcontinues. When the surface temperature of the dielectric reachesequilibrium, i.e., a constant temperature, it stops releasing a charge,and no signal is output. Thus, the pyroelectric sensor is used to detecttemperature changes in an area being monitored.

Once a person enters the area being monitored, a change in thetemperature of the area occurs. The infrared detector can detect thesetemperature changes, e.g., based on the pyroelectric sensor. Thus, basedon signals outputted by the infrared detector, it can be determinedwhether or not someone enters the area being monitored.

However, conventional infrared detectors can only identify temperaturechanges and cannot detect when there is a static infrared signal sourcein the area being monitored. For example, if an elderly person entersthe area being monitored and falls down in the area, a conventionalinfrared detector can only determine if the temperature changes in thearea being monitored. Thus, the detector can determine that someoneenters or leaves the area being monitored, but cannot determine that acontinuous and static infrared signal source exists in the area beingmonitored. Consequently, the conventional detector would fail todetermine that someone fell down in the area being monitored and as aresult the detector cannot generate an alarm in response.

In some typical scenarios that require nursing care and monitoring, webcameras are often used to monitor the area. The camera is used tocapture video images of the area and transmits the video images, forexample, to a nursing station.

However, cameras generally have high power consumption and are poweredby city electricity, which restricts installation and applications ofthe web cameras. In addition, since the web cameras produce images ofthe area being monitored, protecting the privacy of persons in the areabeing monitored restricts their use as well. For example, the webcameras typically cannot be installed in washing rooms and bedrooms.

SUMMARY

An infrared detector is described in this specification that can detecta static infrared signal source while having low power consumption.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in infrared detectors that include apyroelectric sensor; a controller for receiving a trigger signaloutputted by the pyroelectric sensor; a thermopile sensor, wherein thecontroller starts the thermopile sensor after receiving the triggersignal output by the pyroelectric sensor; and an alarm, wherein when thethermopile sensor determines that a difference between a currenttemperature and a background temperature is larger than a thresholdvalue, the controller controls the alarm to generate an alarm signal.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. In particular,one embodiment includes all the following features in combination. Theinfrared detector further includes a timer, wherein the controllerstarts the timer after receiving the trigger signal outputted by thepyroelectric sensor, and starts the thermopile sensor after a countedtime is ended. The alarm is a wireless alarm circuit. The wireless alarmcircuit is a wireless radio frequency (RF) circuit, a Wi-Fi signaltransmitting circuit, or a Bluetooth signal transmitting circuit. Theinfrared detector further includes a battery module, for supplying powerto the pyroelectric sensor and the thermopile sensor.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods that include the actionsof using a thermopile sensor of an infrared detector to determine abackground temperature of an area being monitored; using a pyroelectricsensor of the infrared detector to determine whether a temperature inthe area being monitored has changed; and in response to a determinationthat the temperature has changed: using a thermopile sensor to determinethe temperature in the area being monitored; and comparing thedetermined temperature to the background temperature; determiningwhether the difference between the determined temperature and thebackground temperature satisfies a threshold value; and in response todetermining that the difference satisfies the threshold value,generating an alarm.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. In particular,one embodiment includes all the following features in combination. Afterthe pyroelectric sensor determines that the temperature in the areabeing monitored changed changes, initiating a timer to count down timebefore using the thermopile sensor, and after the counted time is ended,using the thermopile sensor. Generating the alarm includes using awireless alarm circuit. The wireless alarm circuit is a wireless radiofrequency (RF) circuit, a Wi-Fi signal transmitting circuit, or aBluetooth signal transmitting circuit.

The subject matter described in this specification can be implemented inparticular embodiments so as to realize one or more of the followingadvantages. An infrared sensor is provided that can detect both changesin temperature within an area being monitored as well as detect staticinfrared sources. As a result, the infrared detector can improvemonitoring of an area to detect static sources particularly in cases ofmonitoring individuals particularly those under nursing care whileminimizing the impact on individual privacy.

The details of one or more embodiments of the subject matter of thisspecification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example structure of an infrareddetector.

FIG. 2 is a flow chart of an example process for using an infrareddetector.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

This specification describes an infrared detector. The infrared detectoris configured to include both a pyroelectric sensor and a thermopilesensor. The infrared detector can be used to monitor particular regions.For example, the infrared detector can be used to detect activities ofpersons in a specific area being monitored such as a particular room,thereby being applicable to circumstances that involve monitoring ofvulnerable individuals, e.g., nursing.

FIG. 1 is a block diagram of an example structure of an infrareddetector 100. The infrared detector 100 includes a controller 10, apyroelectric sensor 11, a thermopile sensor 12, a timer 13, a wirelessradio frequency (RF) circuit 14, and a rechargeable battery 15.

The controller 10 controls operations of the pyroelectric sensor 11 andthe thermopile sensor 12, and receives signals sent by the pyroelectricsensor 11 and the thermopile sensor 12. Moreover, the controller 10controls the wireless RF circuit 14 to generate an alarm signal whentriggered.

The pyroelectric sensor 11 is used to determine whether anyone enters anarea being monitored such that the temperature changes. When someoneenters the area being monitored and causes temperature changes, e.g.,when a movable infrared signal source enters the area being monitored, asurface temperature of the pyroelectric sensor's 11 dielectric changesand the dielectric releases some electric charge. The pyroelectricsensor 11 is triggered and sends a trigger signal to the controller 10.

The thermopile sensor 12 includes a plurality of thermocouple sensorscoupled in series or in parallel. The thermopile sensor 12 is used tomonitor a static temperature in the area being monitored. In particular,the thermopile sensor 12 detects a static infrared signal source,converts the detected temperature into an electrical signal, anddetermines the temperature in the area being monitored based on theelectrical signal. In some implementations, the thermopile sensor 12enters a sleeping mode in which it does not maintain a working statuscontinuously to save the electrical energy consumed by the infrareddetector 100.

The timer 13 starts counting down a specified amount of time under thecontrol of the controller 10. Once the counted time was elapsed, thetimer 13 outputs a break request signal (BRS) to the controller 10. Thebreak request signal informs the controller 10 that the counted time isended. The specific amount of time set by the timer 13 may be a time setwithin the controller 10. Additionally, in some implementations, thetimer is built as part of the controller 10.

The wireless RF circuit 14 provides the alarm for the infrared detector100. The wireless RF circuit 14 sends an alarm signal, in response to acommand from the controller 10, in a form of a wireless RF signal to abackend control center, e.g., a backend computer or server. Afterreceiving the alarm signal, the control center informs the authorizedindividuals of the alarm. For example, in a nursing context, thecontrolling center can inform a nursing staff to provide help to theperson associated with the alarm.

Alternatively, in some other implementations, the alarm is a wirelessalarm circuit in another form, e.g., a Wi-Fi signal transmittingcircuit, or a BLUETOOTH signal transmitting circuit. These alarmcircuits send wireless signals to the backend control center. Inaddition, the alarm may be a sound and light alarm circuit integratedwith the infrared detector, e.g., a light emitting diode (LED) or buzzerto provide a local audible alarm. The individuals around the infrareddetector 100 respond to the alarm generated by the sound and light alarmcircuit of the infrared detector 100.

The rechargeable battery 15 provides a battery module for the infrareddetector 100 and is used to supply power to the controller 10, thepyroelectric sensor 11, and the thermopile sensor 12. Since thepyroelectric sensor 11 and the thermopile sensor 12 consume low levelsof electrical energy, a typical rechargeable battery 15 can supply astable low-voltage direct current (DC) to satisfy the operationalrequirements of the pyroelectric sensor 11 and the thermopile sensor 12.

FIG. 2 is flow chart of an example process 200 for using an infrareddetector, e.g., infrared detector 100 of FIG. 1. The infrared detectoris activated 202. For example, a battery, e.g., rechargeable battery 15,supplies power to a controller, a pyroelectric sensor, and a thermopilesensor of the infrared detector. The controller can be the controller10, the pyroelectric sensor can be the pyroelectric sensor 11, and thethermopile sensor can be the thermopile sensor 12 of FIG. 1. Thethermopile sensor of the infrared detector collects a backgroundtemperature in an area being monitored, and outputs the collectedtemperature data to the controller. The controller stores the backgroundtemperature data. Then, the thermopile sensor enters a sleeping status(204).

The pyroelectric sensor determines whether anyone enters the area beingmonitored causing a temperature change in the area. If it is determinedthat someone enters the area being monitored, the pyroelectric sensor istriggered, and outputs a trigger signal to the controller (206). If itis determined that someone has not entered the area being monitored, thethermopile sensor terminates the working status (220).

The controller initiates a timer, e.g., the timer 13 of FIG. 1, to startcounting down the specified time (208). The controller determineswhether the counted time is ended (210). If it is determined that thecounted time has ended, yes branch of 210, the controller starts thethermopile sensor. The thermopile sensor collects a temperature in thearea under detection, converts the temperature into an electricalsignal, and outputs it to the controller (212). If the counter time hasnot ended, no branch of 210, the timer continues to count down and thedetermination is repeated. In some implementations, a subsequentdetection of someone entering the area by the pyroelectric sensor resetsthe timer.

The controller compares the collected current temperature in the areabeing monitored with the background temperature (214). The controllerdetermines whether any static infrared signal source exists in the areabeing monitored based on a comparison result (216). If the controllerdetermines that the current temperature of the area being monitored isinconsistent with the background temperature, or a differencethere-between is larger than a threshold value, yes branch of 216, it isdetermined that a static infrared signal source exists in the area underdetection. Consequently, the controller triggers an alert response(218). For example, the alert response can be an alarm provided by awireless RF circuit, e.g., wireless RF circuit 14 of FIG. 1, whichtransmits an alarm signal to a control center.

If the controller determines that the temperature in the area underdetection has not changed or that the difference between the currenttemperature in the area under detection and the background temperatureis smaller than a threshold value, no branch of 216, the controllerdetermines that no static infrared signal source exists in the areaunder detection, the thermopile sensor terminates the working status,and the timer is reset to zero (220).

The infrared detector includes both the pyroelectric sensor and thethermopile sensor in the same package. As a result, the infrareddetector can determine whether a movable infrared signal source existsin the area being monitored as well as determine whether a staticinfrared signal source exists in the area being monitored. The infrareddetector can determine, for example, whether a person falls down in thearea being monitored. In addition, unlike a camera device, thethermopile sensor does not capture images, e.g., photographic images,which protects the privacy of those in the area being monitored. Assuch, the infrared detector can be installed in washing rooms, bedrooms,etc., and can be used to monitor those needing special care, e.g., thoseunder nursing care.

Furthermore, the pyroelectric sensor and the thermopile sensor have lowelectrical energy consumption, and can therefore be constructed suchthat they only need a rechargeable battery instead of being plugged inor directly wired to a building electrical supply. Thus, theinstallation of the infrared detector is versatile.

In some alternative implementations, after the pyroelectric sensor istriggered, the set time of the timer may be adjusted depending upon anactual usage circumstances, or set manually. Alternatively, when thecontroller determines whether a static infrared signal source exists inthe area being monitored, a threshold value for a difference between thebackground temperature and the current temperature may be set manually,e.g., based on particular criteria and environmental conditions.

The infrared detector described above can further be used for otherapplications including in advertisement boards or advertisement boxes.For example, the thermopile sensor first inspects a backgroundtemperature in an area under detection in front of an advertisementboard or advertisement box. Then, the pyroelectric sensor determineswhether anyone passes by, that is, the sensor detects whether thetemperature in the area being monitored changes or not. If thetemperature changes, the thermopile sensor detects the temperature inthe area being monitored once again after a preset time period elapsed,and determines whether the current temperature is consistent with thebackground temperature. If not, it determines that someone stays infront of the advertisement board or advertisement box. In this case, thecontroller, used for controlling the advertisement board oradvertisement box, controls the advertisement board or advertisement boxto operate, e.g., powering on a screen to display images, characters,cartoons, or turning over a displaying board, etc.

Thus, when a person quickly walks by the front area of the advertisementboard or advertisement box, the advertisement board or advertisement boxdoes not display the advertising content or only shows a staticadvertising content. Only when someone stays in front of theadvertisement board or advertisement box, the advertisement board oradvertisement box operates, which reduces electrical energy consumed bythe advertisement board or advertisement box.

It should be noted that, the infrared sensor described in thisspecification is not limited to be above implementations, and changingof the type of an alarm, the type of a timer, and the type of arechargeable battery all fall within the protection scope as claimed.While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinvention or on the scope of what may be claimed, but rather asdescriptions of features that may be specific to particular embodimentsof particular inventions. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various system modulesand components in the embodiments described above should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Particular embodiments of the subject matter have been described. Otherembodiments are within the scope of the following claims. For example,the actions recited in the claims can be performed in a different orderand still achieve desirable results. As one example, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In some cases, multitasking and parallel processing may beadvantageous.

What is claimed is:
 1. An infrared detector, comprising: a pyroelectricsensor; a controller for receiving a trigger signal outputted by thepyroelectric sensor; a thermopile sensor, wherein the controller startsthe thermopile sensor after receiving the trigger signal output by thepyroelectric sensor; and an alarm, wherein when the thermopile sensordetermines that a difference between a current temperature and abackground temperature is larger than a threshold value, the controllercontrols the alarm to generate an alarm signal.
 2. The infrared detectorof claim 1, further comprising: a timer, wherein the controller startsthe timer after receiving the trigger signal output by the pyroelectricsensor, and starts the thermopile sensor after a counted time is ended.3. The infrared detector of claim 1, wherein the alarm is a wirelessalarm circuit.
 4. The infrared detector of claim 3, wherein the wirelessalarm circuit is a wireless radio frequency (RF) circuit, a Wi-Fi signaltransmitting circuit, or a Bluetooth signal transmitting circuit.
 5. Theinfrared detector of claim 1, further comprising: a battery module, forsupplying power to the pyroelectric sensor and the thermopile sensor. 6.The infrared detector of claim 1, wherein the pyroelectric sensordetects entry of an individual to a region being monitored by theinfrared sensor and wherein the thermopile sensor determines whether theindividual remains in the region being monitored.
 7. A methodcomprising: using a thermopile sensor of an infrared detector todetermine a background temperature of an area being monitored; using apyroelectric sensor of the infrared detector to determine whether atemperature in the area being monitored has changed; and in response toa determination that the temperature has changed: using a thermopilesensor to determine the current temperature in the area being monitored;comparing the determined temperature to the background temperature;determining whether the difference between the determined temperatureand the background temperature satisfies a threshold value; and inresponse to determining that the difference satisfies the thresholdvalue, generating an alarm.
 8. The method of claim 7, wherein after thepyroelectric sensor determines that the temperature in the area beingmonitored changed, initiating a timer to count down a specified amountof time.
 9. The method of claim 8, wherein in response to the timer timeelapsing, using the thermopile sensor to determine the currenttemperature of the area being monitored.
 10. The method of claim 7,wherein generating the alarm comprises using a wireless alarm circuit.11. The method of claim 7, wherein the wireless alarm circuit is awireless radio frequency (RF) circuit, a Wi-Fi signal transmittingcircuit, or a Bluetooth signal transmitting circuit.